Compositions, devices and methods for stabilizing and increasing the efficacy of halogen dioxide

ABSTRACT

Compositions and methods for increasing the stability and/or efficacy of chlorine dioxide, and particularly chlorine dioxide generated via electrolysis of chlorite. The present invention further relates to electrolysis devices for producing chlorine dioxide, comprising the stabilizing and efficacy-increasing compositions of the present invention, as well as methods of using both the chlorine dioxide-stabilizing and efficacy-increasing compositions and devices disclosed herein.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. ProvisionalApplication No. 60/471,670, filed May 19, 2003.

FIELD OF THE INVENTION

[0002] The present invention relates to compositions and methods forincreasing the stability and/or efficacy of halogen dioxide, andparticularly chlorine dioxide, generated via electrolysis of salts ofhalogen (and particularly chlorine) dioxide. The present inventionfurther relates to electrolysis devices for producing halogen dioxide,comprising the stabilizing and efficacy-increasing compositions of thepresent invention, as well as methods of using the halogendioxide-stabilizing and efficacy-increasing compositions and devicesdisclosed herein.

BACKGROUND OF THE INVENTION

[0003] Chlorine dioxide, ClO₂, is one of the most effective bleachingagents for use in industrial and domestic process and services, and forcommercial and consumer products. The strong oxidative potential of themolecule makes it ideal for a wide variety of uses that includedisinfecting, sterilizing, and bleaching. Concentrations of chlorinedioxide in an aqueous solution as low as 1 part per million (ppm) orless, are known to kill a wide variety of microorganisms, includingbacteria, viruses, molds, fungi, and spores. Higher concentrations ofchlorine dioxide, up to several hundred ppms, provide even higherdisinfection, bleaching and oxidation of numerous compounds for avariety of applications, including the paper and pulp industry, wastewater treatment, industrial water treatment (e.g. cooling water),fruit-vegetable disinfection, oil industry treatment of sulfites,textile industry, and medical waste treatment.

[0004] Chlorine dioxide offers advantages over other commonly usedbleaching materials, such as hypochlorite and chlorine. Chlorine dioxidecan react with and break down phenolic compounds, and thereby removingphenolic-based tastes and odors from water. Chlorine dioxide is alsoused in treating drinking water and wastewater to eliminate cyanides,sulfides, aldehydes and mercaptans. The oxidation capacity of ClO₂, interms of available chlorine, is 2.5 times that of chlorine. Also, unlikechlorine/hypochlorite, for which bactericidal efficacy is believed todiminish at a pH greater than 7, the bactericidal efficacy of chlorinedioxide is believed to remain effective at pH levels of 7 to 10.Additionally, chlorine dioxide can inactivate C. parvum oocysts in waterat appropriate concentration ranges (i.e. about 100 to 200 ppm) whilechlorine/hypochlorite cannot due to its resistance thereof. Hypochloriteand chlorine both react with the bleached target by inserting thechlorine molecule into the structure of the target. Though this mode ofreaction can be effective, it can result in the formation of one or morechlorinated products, or by-products, which can be undesirable both froma economic sense (to eliminate hydrocarbons from the reaction media) anda safety and environmental standpoint. In addition, the step ofbleaching by hypochlorite and chlorine results in the destruction of thebleach species itself, such that subsequent bleaching requires a freshsupply of the chlorine bleach. Another disadvantage is that certainmicroorganisms that are intended to be killed by these two commonly-usedbleach materials can develop a resistance over time, specifically atlower concentrations of the chlorine or hypochlorite.

[0005] Chlorine dioxide is generally used in an aqueous solution atlevels up to about 1%. It is a troublesome material to transport andhandle at high aqueous concentrations, due to its low stability and highcorrosiveness. This has required end users to generate chlorine dioxideon demand, usually employing a precursor such as sodium chlorite(NaClO₂) or sodium chlorate (NaClO₃). A typical process for generatingchlorine dioxide from sodium chlorate salt is the acid-catalyzedreaction:

NaClO₃+2HCl→NaCl+1/2Cl₂+ClO₂+H₂O

[0006] Sodium chlorite is easier to convert to chlorine dioxide. Atypical process for generating chlorine dioxide from sodium chloritesalt is the acid-catalyzed reaction:

5NaClO₂+4HCl→4ClO₂+5NaCl+2H₂O

[0007] In addition to further identifying novel, on-demand generationdevices for halogen (and particularly chlorine) dioxide, there remainsan equally substantial need to identify compositions that are adapted tostabilize and increase the efficacy of halogen (and particularly)chlorine dioxide solutions upon generation. In some contexts, the use ofsuch compositions would alleviate the need for on-demand chlorinedioxide generation by maximizing the “shelf life” of pre-generated,active chlorine dioxide solutions. In other contexts, the identificationof stabilizing and efficacy-increasing compositions would maximize thestability and performance of halogen dioxide solutions following theiron-demand generation, whether via electrolysis or otherwise. In anyinstance, the halogen dioxide stabilizing and efficacy-increasingcompositions of the present invention address and resolve the quandariesassociated with the contemporary employment of chlorine dioxide,particularly with respect to the low stability of halogen dioxidesolutions.

SUMMARY OF THE INVENTION

[0008] The present invention relates to compositions, devices andmethods for stabilizing and increasing the efficacy of halogen (andparticularly chlorine) dioxide solutions, whether pre-generated orgenerated on-demand. The stabilizing and efficacy-increasingcompositions of the present invention incorporate a hydroxide ionscavenging solution and/or an Interfacial Tension (IFT) lowering agentinto a halogen dioxide solution, whether pre-generated or generatedon-demand. The incorporation of a hydroxide ion scavenging solution intoa halogen (and particularly chlorine) dioxide solution plays a key rolein controlling the pH of the resultant solution—thereby stabilizing theresultant solution for a longer period of time than experienced withoutthe use of a hydroxide ion scavenging system. Further, it is believedthat the incorporation of an Interfacial Tension (IFT) lowering agent,in conjunction with or independent of a hydroxide ion scavenging system,into a halogen dioxide solution maximizes the performance, antimicrobialand otherwise, of the resultant mixture.

[0009] Thus, in accordance with a first aspect of the present invention,compositions for increasing the stability and/or efficacy of halogendioxide, and particularly chlorine dioxide, are disclosed and claimed.In one aspect, a composition for stabilizing a chlorine dioxidesolution, whether pre-generated or generated on-demand, employing ahydroxide ion scavenging system is disclosed. In another aspect, acomposition for increasing the efficacy, antimicrobial and otherwise, ofa chlorine dioxide solution, incorporating an Interfacial Tension (IFT)lowering agent is disclosed. In yet another aspect of the presentinvention, halogen dioxide (and particularly chlorine dioxide) solutionsincorporating both a hydroxide ion scavenging system and an InterfacialTension (IFT) lowering agent are disclosed and claimed. In yet stillother aspects of the present invention, the stabilizing and/orefficacy-increasing compositions of the present invention furthercomprise one or more adjunct ingredients for the provision of certainaesthetic and/or performance benefits to the resultant, halogen dioxidesolution.

[0010] In another aspect of the present invention, electrolysis devicesfor the on-demand generation of stable and efficacious halogen dioxide,and particularly chlorine dioxide, are disclosed and claimed. In oneaspect of the present invention, said devices incorporate a hydroxideion scavenging system for the stabilization of halogen dioxide generatedtherein. In another aspect of the present invention, the electrolysisdevices disclosed herein incorporate an Interfacial Tension (IFT)lowering agent to maximize the efficacy of the halogen dioxide upongeneration. In yet another aspect of the present invention, theelectrolysis devices disclosed herein incorporate both a hydroxide ionscavenging solution and an Interfacial Tension (IFT) lowering agent. Theprecise configuration of the device and/or nature of the compositionwill depend upon the needs and/abilities of the formulator, as well asthe purpose for which use of the device is intended.

[0011] In another aspect of the present invention, methods forstabilizing and/or increasing the efficacy of halogen dioxide (andparticularly chlorine dioxide) solutions, whether pre-generated orgenerated on-demand, are disclosed. In one aspect of the presentinvention, a method for stabilizing halogen dioxide, and particularlychlorine dioxide, is provided. In another aspect of the presentinvention, a method of increasing the efficacy of halogen dioxide, andparticularly chlorine dioxide, is provided. In other aspects, methods ofsanitizing and/or cleaning surfaces using the present compositions areprovided. Said methods generally involve the application of one or moreof the aforementioned, halogen dioxide stabilizing and/orefficacy-increasing compositions to a halogen dioxide solution for whichincreased stability and/or efficacy is desired. In another aspect of thepresent invention, the methods disclosed herein relate to the use of anelectrolysis device employing the present compositions to stabilizeand/or increase the efficacy of halogen dioxide generated on-demand.Other methods disclosed herein relate to the use of the claimed devicesand compositions for application onto a substrate for which sanitationand/or cleaning is desired. The precise steps of each method disclosedherein (and discussed further infra) will depend upon the stabilizingand/or efficacy-increasing composition for which incorporation into ahalogen dioxide solution is sought, the specific needs and/or abilitiesof the formulator and the application for which the use of the methodsclaimed herein is desired.

[0012] In yet still other aspects of the present invention, variousproduct and/or physical forms of the solutions and/or systems describedherein are disclosed. In one aspect of the present invention, a wipecomprising the solutions and/or systems described herein is disclosed.In another aspect of the present invention, the solutions and/or systemsdescribed herein are provided in a gaseous form. In yet another aspectof the present invention, the solutions and/or systems described hereinare provided in a solid form. In yet still another aspect of the presentinvention, the solutions and/or systems described herein are provided ina gel formulation.

DETAILED DESCRIPTION OF THE INVENTION

[0013] As used herein, “stabilizing” is intended to refer to the use ofa hydroxide ion scavenging system in a halogen dioxide, preferablychlorine dioxide, solution to control the hydroxide ion concentration ofsaid solution such that the stability of the resultant solution isgreater than that of a halogen dioxide solution that does not employsuch a system. In this respect, the term “increased stability” isintended to refer to a hydroxide ion scavenging system-comprisinghalogen dioxide solution having at least about 5%, preferably at leastabout 10%, higher halogen dioxide concentration at 25 C, three hoursfollowing formulation thereof versus the concentration of acorresponding halogen dioxide that does not comprise the stabilizingsystem, measured at 25 C and three hours following formulation thereof.

[0014] As used herein, “efficacy-increasing” is intended to refer to theincorporation of a hydroxide ion scavenger and/or IFT lowering agentsinto a halogen dioxide, and particularly chlorine dioxide, solution toconvey one or more antimicrobial performance and/or aesthetic benefitsto said solution. Said benefits include, but certainly are not limitedto, increased antimicrobial kill and/or log reduction in antimicrobialsolutions, improved odor elimination, selective bleaching or colormodification and combinations thereof. In this respect, the term“increased antimicrobial performance” is intended to refer to ahydroxide ion scavenger and/or IFT lowering agent-comprising halogendioxide solution having at least about 5%, preferably at least about 10%greater reduction in the number of microbes than a corresponding halogendioxide solution that does not comprise the hydroxide ion scavengers orIFT lowering agents.

[0015] As used herein, “hydroxide ion scavenging system” is intended torefer to any agent that can be employed into a halogen (or chlorine)dioxide solution and, upon such employment, increase the stability ofsaid solution, particularly when compared to the stability of such asolution that does not incorporate a hydroxide ion scavenging agent.Indeed, the hydroxide ion scavenging agents and/or system of the presentinvention is adapted to increase the concentration of halogen dioxide byat least about 5%, preferably at least about 10%, at 25 C, three hoursfollowing formulation in comparison to the concentration of acorresponding halogen dioxide that does not comprise the stabilizingsystem (also measured at 25 C and three hours following formulationthereof).

[0016] As used herein, the phrases “IFT lowering agents” and/or “IFTsystem” are intended to refer to one or more agents suitable forincorporation into a halogen, and particularly chlorine, dioxidesolution to increase the efficacy, antimicrobial and otherwise, of saidsolution. Agents suitable for use in the halogen-dioxideefficacy-increasing compositions of the present invention are discussedin more detail, infra.

[0017] As used herein, the terms “pre-generated” or “pre-generation” areintended to refer to the generation of halogen dioxide, moreparticularly chlorine dioxide, greater than about 3 hours, preferablygreater than about 2 hours, more preferably greater than about 1 hour,prior to its intended deployment. Such generation may occur at alocation other than that in which deployment of chlorine dioxide isdesired, but may occur at the same location of the intended deployment.

[0018] As used herein, the term “on-demand” is intended to refer to thegeneration of halogen (or chlorine) dioxide less than about 3 hours,preferably less than about 2 hours, more preferably less than about 1hour, prior to the time of intended deployment. In one aspect of thepresent invention, “on demand” is intended to refer to the generation ofhalogen dioxide in less than about 1 second. “On-demand” generation ofchlorine dioxide may typically be effectuated via the use of anelectrolytic device, as disclosed and described infra.

[0019] As used herein, the terms “cleaning and/or disinfecting” areintended to refer to the process of applying (optionally followed byremoving) a composition to a surface or environment with the intent ofremoving and/or inactivating unwanted contaminants.

Compositions for Stabilizing and/or Increasing the Efficacy of HalogenDioxide

[0020] Hydroxide Ion Scavenging System

[0021] In a first aspect of the present invention, compositions forstabilizing and/or increasing the efficacy of halogen, and particularlychlorine, dioxide are disclosed. In one aspect of the present invention,such compositions comprise a hydroxide ion scavenging system. Thehydroxide ion scavenging system of the present invention comprises ahydroxyl ion-reacting agent that is adapted to control the pH of thechlorine dioxide solution to which it is added. By controlling the pH ofa chlorine dioxide solution via the addition of a hydroxyl ion-reactingagent, the solution experiences prolonged stability. Without wishing tobe bound by theory, it is believed that this prolonged stability isattributable to reducing the hydroxyl ion concentration in solution tolower its interaction with dissolved chlorine dioxide. This prolongedstability may also be related to the potential for acidic reaction at alow pH. Reducing the hydroxyl ion concentration to stabilize thechlorine dioxide is useful in static solutions as well as solutions thatundergo high shear, as in the case of turbulent spraying or atomizationof halogen dioxide solutions.

[0022] Generally, the hydroxide ion scavenging system of the presentinvention is employed into a chlorine dioxide solution at a level offrom about 0.001 to about 10%, preferably 0.01 to about 7.5%, morepreferably 0.05 to about 5%, most preferably 0.1 to about 2.5%, byweight of the total hydroxide ion scavenging system-comprising chlorinedioxide solution. A person of ordinary skill in the art will readilyappreciate that the exact amount of hydroxide ion scavenging agentneeded to stabilize a chlorine dioxide solution will depend upon manyfactors including, but not limited to, the nature of the hydroxide ionscavenging agent, the concentration of the halogen dioxide solution forwhich the conveyance of increased stability is desired and thegeneration method of the halogen dioxide solution under consideration.Suitable hydroxide ion scavenging agents for use in the presentinvention are selected from the group consisting of: organic acids,salts of organic acids, inorganic acids, salts of inorganic acids, andthe like. It should be noted that the hydroxide ion scavenging agents ofthe present invention are adapted to stabilize any halogen dioxidesolution.

[0023] Interfacial Tension (IFT) Lowering System

[0024] In another aspect of the present invention, an InterfacialTension (IFT) lowering system for stabilizing and/or increasing theefficacy of a halogen dioxide solution is disclosed. Without wishing tobe bound by theory, it is believed that the addition of one or moreIFT-lowering agents to a halogen dioxide (and particularly chlorinedioxide) solution provides the overall effect of increasing the efficacyof said solution by lowering the Interfacial Tension of the resultantsystem. Without wishing to be bound by theory, it is believed that theIFT-lowering agents of the present invention are adapted to reduce thetension at the interface between two physical phases—thereby decreasingthe level of work and/or energy required to expand the interfaces. Theability of the present IFT-lowering agents to encourage expansion of theinterfaces with decreased energy is believed to facilitate penetrationand increased interfacial exposure of halogen dioxide (and particularlychlorine dioxide). Moreover, the IFT-lowering agents of the presentinvention can exhibit synergy in concert with halogen dioxides—therebyfacilitating microbe structure and protein denaturing. It is furtherbelieved that surfactants forming a monolayer of surfactant at airinterfaces can be used to regulate halogen dioxide partitioning into thesurrounding air. This may be of special interest for situations in whichhalogen dioxide solutions comprising the present IFT-lowering agents areused in the context of decontamination, whether via chamber, spray orother means.

[0025] Depending on the spray device and IFT-lowering agent employed,the sprayed particle size of the aqueous, halogen dioxide solution canbe controlled and optimized for the particular application. In somecases, very small particle sizes may increase the surface area enough toovercome surfactant barrier effects thus helping to facilitate thepartitioning of the halogen (chlorine) dioxide into the gas/air phase.In such an instance, a transition from aqueous chlorine dioxide exposureto gas phase chlorine dioxide exposure occurs, which may be beneficialin delivering the subject compositions to areas that are difficult toreach using aqueous dispersions. Use of small particle sizes may also bedesirable for situations in which substrate contact with the aqueoussolution is not desired. Copious levels of foam on a surface likewisemay serve as an additional physical barrier to halogen dioxide loss fromsolution to the surrounding atmosphere.

[0026] Of course, the precise composition of the presentefficacy-increasing IFT-lowering systems will depend on the purpose forwhich employment of the resultant chlorine dioxide solution is desiredand the needs and/or abilities of the formulator. Nevertheless, theIFT-lowering system and/or agents of the present invention arepreferably incorporated into a halogen dioxide solution at a level offrom about 0.00001 to about 10%, preferably from about 0.0001 to about5%, more preferably from about 0.0005 to about 2%, most preferably 0.001to about 1%, by weight of the total, IFT-lowering system-containinghalogen dioxide solution. Of course, in a particularly preferredembodiment of the present invention, the IFT-lowering agents disclosedherein are incorporated, in the above-listed amounts, into a chlorinedioxide solution for which increased stability and/or efficacy isdesired.

[0027] A wide variety of IFT-lowering agents can be used to stabilizeand/or increase the efficacy of a halogen dioxide solution in accordancewith the present invention. Although a few such agents have beenincluded herein, it should be appreciated that other agents can providesimilar benefits in increasing the efficacy of the halogen dioxidesolutions to which they are added. Indeed, there exist several classesof agents that can be used as IFT-lowering agents for purposes of thepresent invention. These classes include, but certainly are not limitedto: IFT-lowering polymers, IFT-lowering solvents, IFT-loweringsurfactants and combinations thereof. In a particularly preferred aspectof the present invention, IFT-lowering surfactants are employed intohalogen dioxide solutions to convey the aforementioned benefits affordedby the present IFT-lowering agents disclosed herein. IFT-loweringsurfactants for use in increasing the efficacy and/or performance of thehalogen dioxide solutions disclosed herein can be nonionic, anionic,amphoteric, amphophilic, zwitterionic, cationic, semi-polar nonionic,and mixtures thereof. Nonlimiting examples of such surfactants aredisclosed in U.S. Pat. Nos. 5,707,950 and 5,576,282, incorporated hereinby reference. A typical listing of anionic, nonionic, amphoteric andzwitterionic classes, and species of these surfactants, is provided inU.S. Pat. No. 3,664,961 issued to Norris on May 23, 1972, andincorporated herein by reference.

[0028] Nonlimiting examples of IFT-lowering surfactants useful hereininclude the conventional C₈-C₁₈ alkyl ethoxylates and/or alcoholethoxylates (AE), with EO about 1-22, including the so-called narrowpeaked alkyl ethoxylates and C₆-C₁₂ alkyl phenol alkoxylates (especiallyethoxylates and mixed ethoxy/propoxy), alkyl dialkyl amine oxide,alkanoyl glucose amide, C₁₁-C₁₈ (linear) alkyl benzene sulfonates (LAS)and primary, secondary and random alkyl sulfates (AS and/or SAS), theC₁₀-C₁₈ alkyl alkoxy sulfates (AES), the C₁₀-C₁₈ alkyl polyglycosidesand their corresponding sulfated polyglycosides (APG), C₁₂-C₁₈alpha-sulfonated fatty acid esters, C₁₂-C₁₈ alkyl and alkyl phenolalkoxylates (especially ethoxylates and mixed ethoxy/propoxy), C₁₂-C₁₈betaines and sulfobetaines (“sultaines”), C₁₀-C₁₈ amine oxides, alphaolefin sulfonates (AOS), alcohol ethoxy sulfates, sodium paraffinsulfonates, amido propyl amines, alkyl N-methyl glucamides,nitrilotriacetic acid (NTA), alkali metal salts of natural fatty acidsand the like. Other conventional useful surfactants are listed instandard texts.

[0029] In another aspect of the present invention, IFT-lowering polymersand/or IFT-lowering solvents are incorporated into halogen dioxide (andparticularly chlorine dioxide) solutions for which the conveyance ofincreased stability and/or efficacy are desired. Suitable IFT-loweringpolymers for use in the context of the present invention include, butcertainly are not limited to: polyoxyalkylene block copolymers. Indeed,suitable IFT-lowering solvents for use as IFT-lowering agents, in thecontext of the present invention include, but certainly are not limitedto: glycol ethers such as propylene glycol n-propyl ether. Of course,the selection of the appropriate IFT-lowering agent for use in thecontext of the present invention will depend upon several factors, someof which include: (1) Sufficient chemical compatibility between thehalogen dioxide and IFT lowering agent; (2) the nature of the halogendioxide solution for which the conveyance of increased stability and/orefficacy is desired; (3) the purpose for which deployment of theresultant, IFT-lowering agent-containing halogen dioxide solution isdesired; and (4) the needs and/or abilities of the formulator of thepresent compositions.

[0030] Hydroxide Ion-Scavenging and IFT-Lowering Systems

[0031] In another aspect of the present invention, the halogen dioxidecompositions disclosed herein comprise both a hydroxide ion-scavengingsystem and an IFT-lowering system. Such compositions are adapted tostabilize halogen dioxide, and particularly chlorine dioxide, for aprolonged period and convey certain aesthetic and/or performancebenefits to said solution. Indeed, it has been surprisingly discovered,and documented via the present disclosure, that synergy is exhibited viathe employment of both a hydroxide ion scavenging and IFT-loweringsystem in a halogen dioxide solution. Without wishing to be bound bytheory, it is believed that the dual employment of an hydroxide ionscavenger and IFT lowering agent like a surfactant serves the integralpurpose of maximizing the amount of halogen dioxide delivered to thedesired interface by facilitating maximum surface area coverage fromlowered interfacial tension while maintaining higher intrinsic halogendioxide concentrations via inhibited degradation. Indeed, the hydroxideion scavenging system and IFT-lowering systems of the present invention,when employed in combination, are present in an amount of from about0.00001 to about 15, preferably from about 0.0001 to about 10%, morepreferably from about 0.0005 to about 5%, most preferably from about0.001 to about 2.5%, by weight of the total, hydroxide ion scavengingsystem and surfactant system-containing chlorine dioxide solution.

[0032] Adjunct Ingredients

[0033] In yet another aspect of the present invention, the halogendioxide stabilizing and efficacy-increasing compositions disclosedherein will comprise one or more adjunct ingredients for providingaesthetic and/or performance benefits to the resultant composition. Inone aspect of the present invention, the hydroxide ion scavengingcontaining compositions will comprise one or more adjunct ingredients(as discussed further infra). In another aspect of the presentinvention, the IFT-lowering system-containing compositions will compriseone or more adjunct ingredients. In yet another aspect of the presentinvention, the adjunct ingredients disclosed herein are incorporatedinto a halogen dioxide solution comprising both a hydroxide ionscavenging system and an IFT-lowering system.

[0034] While not essential for the purposes of the present invention,several conventional cleaning adjunct materials illustrated hereinafterare suitable for use in the present compositions and may be desirablyincorporated in preferred embodiments of the present invention, forexample to assist or enhance cleaning performance, for treatment of thesubstrate to be cleaned, or to modify the aesthetics of the presentcomposition as is the case with perfumes, colorants, dyes or the like.The precise nature of these additional components, and levels ofincorporation thereof, will depend on the physical form of thecomposition and the nature of the cleaning operation for which its useis intended.

[0035] Adjuncts suitable for incorporation into the halogen (andparticularly chlorine) dioxide stabilizing and efficacy-increasingcompositions of the present invention include, but certainly are notlimited to: bleaching systems, enzymes and enzyme stabilizers, builders,dispersants, soil release agents, chelating agents, suds suppressors,softening agents, dye transfer inhibition agents, non-phosphatebuilders, color speckles, silvercare, anti-tarnish and/or anti-corrosionagents, dyes, fillers, germicides, alkalinity sources, hydrotropes,anti-oxidants, perfumes, solubilizing agents, carriers, processing aids,pigments, and pH control agents as described in U.S. Pat. Nos.5,705,464, 5,710,115, 5,698,504, 5,695,679, 5,686,014 and 5,646,101, allof which are incorporated herein by reference.

Devices Comprising the Stabilizing and Efficacy-Increasing Compositions

[0036] In another aspect of the present invention, devices comprisingthe stabilizing and/or efficacy-increasing compositions of the previousaspect are disclosed and claimed. Said devices are generally limited tothose that are adapted to generate halogen dioxide from halogen dioxidesalt precursors, on-demand (as defined supra). Nevertheless, thestabilizing and efficacy-increasing compositions of the presentinvention may further be employed to stabilize and/or increase theefficacy of halogen dioxide that is pre-generated. A completedescription of suitable electrolysis devices for use in conjunction withthe stabilizing and efficacy-increasing compositions of the presentinvention is included in U.S. patent application Ser. No. 09/947,846filed in the United States Patent and Trademark Office on 20 Sep. 2001,and published on 09 Jan. 2003. This application is incorporated, in itsentirety, herein by reference.

[0037] In one aspect of the present invention, suitable on-demandgeneration devices for use with the stabilizing and/orefficacy-increasing systems disclosed herein employ an electricalcurrent passing through an aqueous feed solution between an anode and acathode to convert a halogen dioxide salt precursor dissolved within thesolution into a halogen dioxide. When an aqueous solution flows throughthe chamber of the electrolysis cell, and electrical current is passedbetween the anode and the cathode, several chemical reactions occur thatinvolve the water, as well as one or more of the other salts or ionscontained in the aqueous solution. These chemical reactions, and otherfeatures of the generation device that can be used in accordance withthis aspect of the present invention, are described in co-pending U.S.patent application Ser. No. 09/947,846 filed in the United States Patentand Trademark Office on 20 Sep. 2001. The Applicants hereby incorporatethe subject matter of this patent application, and particularly itsdisclosure with respect to the precise characteristics of on-demandgeneration devices for use in the context of the present invention,herein.

[0038] Multiple Chamber-Comprising Electrolysis Device

[0039] In yet another aspect of the present invention, the on-demandgeneration device described in U.S. patent application Ser. No.09/947,846 (and incorporated herein by reference) may compriseadditional chambers that facilitate the mixing of greater than onesolution to form the stabilizing and efficacy-increasing compositions ofthe present invention. Indeed, separation of the subject compositions todelay mixing until use of the resultant halogen dioxide solution isdesired, is particularly useful when using chlorite salts and the totalmixture comprises a pH that of less than about 7 and preferably lessthan about 5. In one aspect of the present invention, this is achievedby separating a chlorite salt solution and a low pH surfactant solution.In yet another aspect of the present invention, this is achieved byseparating a chlorite salt solution containing the surfactant and asecond, low pH solution having other ingredients.

[0040] In the case of this “on-demand” generation, electrolysis inaccordance with the present invention could occur in a number of ways.Nevertheless, in any instance, electrolysis should occur down stream ofthe chlorite-based solution or resultant mixture. In one aspect of thepresent invention, this would be accomplished by mixing two streams,following electrolysis of the chlorite (halite) stream. In yet anotheraspect of the present invention, on-demand electrolysis could beaccomplished by mixing two streams, said mixing being prior toelectrolysis of the chlorite-containing total mixture.

[0041] The practitioner of the present invention will appreciate thatthere exist several mechanisms adapted to achieve the above-described,requisite mixing. In one aspect of the present invention, one commonpump, which is adapted to create suction sufficient to draw both streamsis employed to achieve requisite mixing. In yet another aspect of thepresent invention, a pump is employed to draw one stream and a venturiis employed after discharge thereof to draw and mix in a second stream.In yet another aspect of the present invention, two pumps pullingseparate streams that are mixed after the pumps are employed. In anotheraspect of the present invention, electrolysis can occur before or aftera pump or venturi. Nevertheless, it is generally more practical to use adevice that is adapted to engage in electrolysis after any streams arepumped so as to prevent any negative impact on the performance of thepump caused by gas formed during the electrolysis.

[0042] In another aspect of the present invention, devices producing thestabilizing and efficacy-increasing compositions are not restricted toformation of halogen (chlorine) dioxide by electrolysis. In particular,the aforementioned aspect relating to the mixture of more than onesolution can be constructed and/or configured such that the halogendioxide is produced from chemical reactions upon mixing. Non-limitingexamples of such a configuration include mixing a low pH solution with ahalite solution to facilitate halogen dioxide production by haliteacidification. In such an instance, a pH of less than about 2 ispreferred for rapid halogen dioxide formation. Another example relatesto the mixing of a liquid hypochlorite solution with a solutioncontaining excess chlorite salt at low pH to form chlorine dioxide. Insuch an instance, a pH of less than about 4 is preferred. In the case offorming halogen dioxide via chemical means when mixing two (or more)streams, the mixing could be accomplished via a number of mechanismsincluding, but not limited to, one common pump creating suction to drawboth streams, a pump on one stream and a venturi after its dischargewhich is used as intake to mix in a second stream, and two pumps pullingseparate streams that are mixed after the pumps (as hereinbeforedescribed).

[0043] In yet another aspect of the present invention, when additionalchloride salt is used to facilitate electrolysis of chlorine intochlorine dioxide, the side reaction of electrolysis of Cl⁻ tohypochlorite, OCl⁻, may be controlled via use of a hydroxyl ionscavenger in the form of specific acidic buffers. In one aspect, it maybe desirable to have some OCl⁻ present with the chlorine dioxide, in,for example, situations in which increased antimicrobial efficacy isdesired. In such an instance, by utilizing a hydroxyl ion scavenger andcontrolling the final pH to between about 2 and about 7, one canfacilitate the conversion of OCl⁻ ion to HOCl. For anitmicrobialefficacy, HOCl is generally a preferred species to use. Above a pH ofabout 7, OCl⁻ is the predominant species, and at a pH of below about 2,Cl₂ predominates. For situations in which the presence of thehypochlorite species it is not desirable, the solution may be formulatedto produce excess chlorite that has not reacted from the electrolysis.This excess chlorite can subsequently react with the HOCl generated fromthe electrolysis to form additional chlorine dioxide. The preferred pHfor this type of a reaction is less than about 4.

[0044] Virtual Membrane

[0045] In yet another aspect of the present invention, electrolysisdevices in accordance with the present invention further compriseparallel plate electrodes configured such that a virtual (e.g. quasi,pseudo) membrane is formed. The virtual membrane of the presentinvention is not a permanent physical membrane, but rather, is afluid-like membrane that is formed by the flow characteristics of thefluid solution undergoing electrolysis. Specifically, the flow withinthe parallel plates of the electrolysis devices disclosed herein iscontrolled such that the Reynolds number associated with the fluid isless than about 2000. Without wishing to be bound by theory, maintaininga Reynolds number below about 2000 establishes a fluid flow regimewithin the electrolytic cell that is configured in a planar form,parallel to the plates. This configuration is believed to facilitatetransverse ion transport in solution as a result of the appliedelectrical potential, while minimizing and/or eliminating bulk fluidmixing normal to the electrolysis plates to prevent undesiredjuxtaposition and/or reaction of the byproducts of the electrolyticreaction. A description of the application of the present virtualmembrane in the context of the electrolysis devices herein disclosed inprovided in the “Examples” section of the present disclosure.

Methods of Using Stabilizing and/or Efficacy-Increasing Compositions andElectrolysis Devices

[0046] In yet another aspect of the present invention, methods ofstabilizing and increasing the efficacy of halogen (and particularlychlorine) dioxide are disclosed. In one aspect, a method of stabilizinga halogen dioxide solution is disclosed. Said method comprises the stepsof incorporating a hydroxide ion-scavenging solution in accordance withthe first aspect of the present invention into a halogen, preferablychlorine, dioxide solution for which increased stability is desired. Inanother aspect of the present invention, a method for increasing theefficacy of a halogen dioxide solution is disclosed. Said methodgenerally comprises the step of incorporating an IFT-lowering agentand/or system in accordance with the first aspect of the presentinvention into a halogen, preferably chlorine, dioxide solution forwhich increased efficacy and/or performance is desired. In yet anotheraspect of the present invention, a method of both stabilizing andincreasing the efficacy of a halogen dioxide solution is disclosed. Saidmethod generally comprises the steps of adding both a hydroxideion-scavenging solution and an IFT-lowering system and/or agent to ahalogen dioxide, preferably chlorine dioxide, solution for whichincreased stability and/or efficacy is desired

[0047] In another aspect of the present invention, a method ofstabilizing and/or increasing the efficacy of halogen (and particularlychlorine) dioxide solutions generated via electrolysis is disclosed.Said methods comprise the steps of introducing the stabilizing and/orefficacy-increasing compositions of the present invention into a deviceadapted to electrolyze halite salt (as hereinbefore described), andfacilitating the mixture of said stabilizing and/or efficacy-increasingcompositions with the resultant halogen dioxide mixture.

Product and/or Physical Forms Comprising Halogen Dioxide Solutions:Hydroxide Ion Scavenging System-Comprising Halogen Dioxide Solutions;and/or IFT-Lowering System-Comprising Halogen Dioxide Solutions

[0048] In yet another aspect of the present invention, various productforms of the solutions and/or systems described herein are provided.Indeed, in one aspect of the present invention the solutions and/orsystems described herein are formulated into gel. In accordance withthis aspect of the invention, the gel may be formulated by adding anysuitable thickener to a halogen dioxide solution, a hydroxide ionscavenging system-comprising halogen dioxide solution and/or anIFT-lowering system-comprising halogen dioxide solution. Without wishingto be bound by theory, it is believed that incorporation of the presentsolutions and/or systems into such a gel facilitates adherence of thegel to the target surface and/or substrate for which the conveyance ofthe subject solution and/or system is desired. Further, and withoutwishing to be bound by theory, it is believed that formulation of thepresent systems into a gel will result in lower degradation by limitingmass transfer and/or loss of halogen dioxide to the atmosphere. Thoseskilled in the art to which the subject invention pertains, will readilyappreciate the multitude of thickeners and methods suitable for use informulation of the present gels.

[0049] In yet another aspect of the present invention, the solutionsand/or systems described herein are incorporated into a wipe product. Inthis aspect of the invention, halogen dioxide is generated viaencapsulation of reactive species into or onto a wipe. The wipe may thenbe “activated,” thereby generating halogen dioxide, via shearing thewipe and/or by electrolyzing a wipe comprising one or more halogendioxide salt precursors. In another aspect of the present invention, thewipe comprising one or more halogen dioxide salt precursors iselectrolyzed via passage through and/or between the electrolysis platesbetween which electrolysis of the halogen dioxide salt precursorsoccurs. In yet another aspect of the present invention, a wipecomprising one more of the solutions and/or systems disclosed herein maybe treated in a chamber, in which the halogen dioxide salt precursorsincluded in said wipe are electrolyzed to generate halogen dioxide. Inyet still another aspect of the present invention, the wipe disclosedherein is sprayed with a halogen dioxide solution prior to an intendeduse. In yet another aspect of the present invention a wipe comprising ahydroxide ion scavenging system and/or an IFT-lowering system is sprayedwith a halogen dioxide solution prior to an intended use.

[0050] In yet still other aspects of the present invention, the systemsand/or solutions disclosed herein are formulated into an aerosol and/orgaseous phase, adapted to fumigate a surface and/or area for which theconveyance of stabilized and/or efficacious halogen dioxide is desired.In one aspect of the present invention, a halogen dioxide solution ispresented in an aerosol and/or gaseous phase. In yet another aspect ofthe present invention, a hydroxide ion scavenging system-comprisinghalogen dioxide solution and/or an IFT-lowering system-comprisinghalogen dioxide solution is presented in an aerosol and/or gaseousphase. In yet still another aspect of the present invention, the halogendioxide solution, hydroxide ion scavenging system-comprising halogendioxide solution and/or an IFT-lowering system-comprising halogendioxide solution disclosed herein are presented in a solid phase forconveyance to a target surface.

PREPARATIVE EXAMPLES Example 1

[0051] Chlorine Dioxide Solution Comprising a Hydroxide Ion ScavengingSystem.

[0052] The following is an example of a chlorine dioxide solutioncontaining a hydroxide ion scavenger in the form of citric acid. Thissolution contains about 120 ppm chlorine dioxide. Ingredient Wt % Sodiumchloride 0.057 Sodium chlorite 0.024 Chlorine dioxide 0.012 Sodiumhydroxide 0.009 Sodium carbonate 0.001 Citric acid 0.093 Water 99.804

Example 2

[0053] Chlorine Dioxide Solution Comprising a Surfactant System

[0054] The following is an example of a chlorine dioxide solutioncontaining the anionic surfactant Sodium Lauryl Sulfate (SLS). Thissolution contains about 120 ppm chlorine dioxide. Ingredient Wt % Sodiumchloride 0.057 Sodium chlorite 0.024 Chlorine dioxide 0.012 Sodiumhydroxide 0.009 Sodium carbonate 0.001 Sodium Lauryl Sulfate 0.012 Water99.885

Example 3

[0055] Chlorine Dioxide Solution Comprising a Surfactant System

[0056] The following is an example of a chlorine dioxide solutioncontaining the nonionic surfactant APG or AlkylPolyGlucoside (trade nameGlucopon). This solution contains about 120 ppm chlorine dioxide.Ingredient Wt % Sodium chloride 0.057 Sodium chlorite 0.024 Chlorinedioxide 0.012 Sodium hydroxide 0.009 Sodium carbonate 0.001 Glucopon 4250.012 Water 99.885

Example 4

[0057] Chlorine Dioxide Solution Comprising a Hydroxide Ion ScavengingSystem and Surfactant System

[0058] The following is an example of a chlorine dioxide solutioncontaining hydroxide ion scavenger citric acid and anionic surfactantSLS. A hydroxyl ion source is added to interact with the citric acid andadjust the mix pH to about 4. This solution contains about 100 ppmchlorine dioxide. Ingredient Wt % Citric acid (anhydrous) 0.078 Sodiumhydroxide 0.007 Sodium Lauryl Sulfate 0.010 Sodium carbonate 0.006Magnesium carbonate hydroxide 0.002 PPG 2000 0.004 Antifoam 2-4293 0.001Grapefruit oil 0.0001 Sodium chloride 0.048 Sodium chlorite 0.020Chlorine dioxide 0.010 Water 99.8139

Example 5

[0059] Device Comprising Hydroxide Ion Scavenging and Surfactant Systems

[0060] An electrolysis cell of the general design depicted in FIG. 1 ofcopending U.S. patent application Ser. No. 09/947,846 (published 20 Sep.2001 and incorporated herein by reference) was used to convert anaqueous solution comprising sodium chlorite into an effluent solutioncomprising chlorine dioxide. The electrolysis cell had a pair ofconfronting electrodes having a passage gap of about 0.19 mm. The anodewas made of ES300-titanium, coated with ruthenium oxide and iridiumoxide. The cathode was made of 201 stainless steel. The dimensions ofthe planar electrodes were 75.2 mm long by 25.4 mm wide.

[0061] The aqueous feed solution was prepared by mixing 10 liters ofde-ionized water with 62.6 gms technical grade sodium chlorite stock(80% active, Aldrich Chemical Company, Inc, Milwaukee, Wis. 53233; Cat.No. 24415-5) with a stirring bar until dissolved, forming a 5000 ppmsodium chlorite salt solution. The aqueous feed solution was retained ina 15-liter glass container placed within a light-proof box and cooled to5 degrees Celsius. A peristaltic pump metered the aqueous feed solutionfrom the glass container through the electrolysis cell at a flow rate of300 ml/minute. A direct current of 5.72 amps was applied across theelectrodes by a DC power supply to provide a voltage potential of 4.5volts across the electrolysis cell. The effluent solution was withdrawnfrom the electrolysis cell and analyzed. The effluent contained 109 ppmchlorine dioxide and 4891 ppm of un-reacted sodium chlorite, for achlorite conversion of 2.9%.

[0062] The following examples were prepared to document use of a singlesolution containing hydroxide ion scavengers and a surfactant systemcapable of running through a sprayer device equipped with anelectrolysis cell to generate chlorine dioxide from sodium chlorite inthe solution. A phosphate based version and carbonate based version arepresented. Ingredient Wt % Wt % Citric acid (anhydrous) 0.2 0.23 NaOH(50% soln.) 0.24 0.17 Sodium Lauryl Sulfate 0.05 0.05 Na₂HPO₄ 0.03 —NaH₂PO₄.H₂O 0.03 — NaHCO₃ — 0.10 NaClO₂ 0.5 0.50 Water 98.95 98.95

[0063] The solutions comprise a pH between about 6 and 7 before theelectrolysis, and maintained a pH between 6 and 9 after electrolysis isconducted. The discharge from the electrolysis cell and pump wasestimated to have a chlorine dioxide level of 85 ppm. This solution canalso be recycled through the cell/pump to further increase the chlorinedioxide concentration. The effluent from the cell/pump was subsequentlydischarged through a atomizing spray nozzle to create a fine mist ofchlorine dioxide containing particles. The mist can be used to coversurfaces for treatment, or confined in a enclosed area to have a“fumigation” effect.

[0064] For the examples that follow, reference these componentcompositions: Ingredient Wt % I Deionized Water 99.9 Sodium Chlorite0.05 stock (technical grade) Sodium Chloride 0.05 II Deionized Water 97NaHCO₃ 1.77 Sodium Lauryl 1.23 Sulfate III Deionized Water 99.59 Citricacid 0.41 (anhydrous) IV Deionized Water 99.42 Acid - Anionic 0.58powder mix (V) V Citric acid 77.61 (anhydrous) Sodium Lauryl 10.31Sulfate Na2CO3 5.28 MgCO3 2.00 PPG 2000 3.7 Antifoam 2-4293 1.00Grapefruit oil 0.10

[0065] The following examples utilize the compositions above.

[0066] Examples A & E: Composition I was electrolyzed while being pumpedthrough an electrolytic plate using 6.6 volts. A final mixture was thencreated comprising 83% of electrolyzed composition I and 17% deionizedwater.

[0067] Examples B & F: Composition I was electrolyzed while being pumpedthrough an electrolytic plate using 6.6 volts. A final mixture was thencreated comprising 83% of electrolyzed composition I and 17% compositionII.

[0068] Examples C & G: Composition I was electrolyzed while being pumpedthrough an electrolytic plate using 6.6 volts. A final mixture was thencreated comprising 83% of electrolyzed composition I and 17% compositionIII.

[0069] Examples D & H: Composition I was electrolyzed while being pumpedthrough an electrolytic plate using 6.6 volts. A final mixture was thencreated comprising 83% of electrolyzed composition I and 17% compositionIV.

[0070] Microbiological efficacy testing was conducted utilizing theexample compositions A-H described above. The lower the Log Recoverynumber the better the performance.

Gram Positive Bacteria in Surface Spray Test

[0071] Organism: S. aureus

[0072] Target ClO₂ solution concentration: 50 ppm

[0073] 5 minute treatment time B C D A ClO₂ + ClO₂ + ClO₂ + Acid/ ClO₂only Alkaline/Surfactant Citric acid Surfactant (pH˜10.5) (pH˜9)(pH˜3.5) (pH˜4) Log 6.02 2.52 1.57 0.62 Recovery

Gram Negative Bacteria in Surface Spray Test

[0074] Organism: P. aeruginosa

[0075] Target ClO₂ solution concentration: 50 ppm

[0076] 5 minute treatment time F G H E ClO₂ + ClO₂ + ClO₂ + Acid/ ClO₂only Alkaline/Surfactant Citric acid Surfactant (pH˜10.5) (pH˜9)(pH˜3.5) (pH˜4) Log 6.32 4.79 3.16 0* Recovery

[0077] The next examples utilize the following component compositions:Ingredient Wt % VI Deionized Water 99.75 Sodium Chlorite 0.25 stock(technical grade) VII Deionized Water 99.00 Acid - Anionic 1.00 powdermix (V) VIII Deionized Water 99.29 Citric acid 0.71 (anhydrous)

[0078] The following examples utilize the compositions above.

[0079] Example J: Composition VI was electrolyzed while being pumpedthrough an electrolytic plate using 6 volts. A final mixture was thencreated comprising 50% of electrolyzed composition VI and 50% deionizedwater.

[0080] Example K: Composition VI was electrolyzed while being pumpedthrough an electrolytic plate using 6 volts. A final mixture was thencreated comprising 50% of electrolyzed composition VI and 50%composition VIII.

[0081] Example L: Composition VI was electrolyzed while being pumpedthrough an electrolytic plate using 6 volts. A final mixture was thencreated comprising 50% of electrolyzed composition VI and 50%composition VII.

[0082] Microbiological efficacy testing was conducted utilizing theexample compositions J-L described above. The lower the Log Recoverynumber the better the performance.

Gram Positive Spores in Suspension Test

[0083] Organism: Bacillus cereus spores

[0084] ClO₂ solution concentration: ˜85 ppm

[0085] 5 minute treatment time J K L ClO₂ only ClO₂ + Citric acid ClO₂ +Acid/Surfactant (pH˜10.5) (pH˜3.5) (pH˜3.5) Log Recovery 0.67 0.56<0.30*

Example 6

[0086] Stable and Efficacious Chlorine Dioxide Mixes Produced from aSpray Bottle Having Two Compartments

[0087] Solutions M and N are in the separate compartments and are mixedtogether by a small centrifugal pump pulling equal amounts from eachcompartment and mixing together at the suction, and further in the pump.The product is discharged from the pump through a spray nozzle. Thedischarge mixture has formed chlorine dioxide as a result of mixing thetwo components M+N, and the mix has the characteristic yellow appearanceof a chlorine dioxide solution which stays stable and with thesurfactant represents an effective antibacterial product. Ingredient Wt% M DI Water 99.12 Citric Acid 0.78 Sodium Lauryl 0.10 Sulfate N DIWater 99.45 Na ClO₂ stock 0.08 NaOCl stock 0.47 (5.25% NaOCl active instock)

Example 7

[0088] Determination of Reynolds Number (Re) in Parallel PlateElectrodes for Formation of Virtual Membrane:

[0089] For a full channel, the hydraulic radius is the cross sectionarea divided by the wetted perimeter R_(h)=A/P. For a non-circular pipe,the hydraulic diameter is four times the Hydraulic radius. D_(h)=4R_(h)

[0090] For a parallel plate channel of width w, and spacing s, thehydraulic radius would be w*s/(2*(w+s)). The hydraulic diameter is4R_(h) or D_(h)=2w*s/(w+s). For a channel where w>>s, D_(h) becomesabout 2s.

Re=D _(h) Vp/u(˜2sVp/u when w>>s)

[0091] total volumetric flow Q 144 cm{circumflex over ( )}3/min cellwidth w 2.5 Cm cell spacing s 0.02 Cm flow cross section A 0.05cm{circumflex over ( )}2 number of cells n 1 fluid density p 1gm/cm{circumflex over ( )}3 fluid dynamic viscosity u 1 CP cell flowvelocity V 48 cm/sec Characteristic diameter Dh 0.039683 Cm cell lengthl 7.2 Cm Reynolds number Re 190.4762 Residence Time RT 0.0025 Min CellVolume Vol 0.36 cm{circumflex over ( )}3

[0092] All documents cited in the Detailed Description of the Inventionare, in relevant part, incorporated herein by reference; the citation ofany document is not to be construed as an admission that it is prior artwith respect to the present invention.

[0093] While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A hydroxide ion scavenging system for stabilizinga halogen dioxide solution, said system comprising (a) from about 0.001%to about 10% by weight of the total of a hydroxide ionscavenger-comprising halogen dioxide precursor solution, a hydroxide ionscavenging system; and (b) from about 0.000001% to about 50% by weightof the total of a hydroxide ion scavenging-comprising halogen dioxideprecursor solution, one or more halogen salt precursors; wherein agentsfor use in said hydroxide ion scavenging system are selected from thegroup consisting of: organic acids, salts of organic acids, inorganicacids, salts of inorganic acids, and mixtures thereof; further whereinsaid hydroxide ion scavenging system is adapted to increase theconcentration of a halogen dioxide solution by at least about 5% incomparison to the concentration of a corresponding halogen dioxidesolution that does not comprise said hydroxide ion-scavenging system,when both solutions are measured at 25° C., three hours followinghalogen dioxide generation.
 2. The hydroxide ion scavenging system ofclaim 1, wherein halogen dioxide is pre-generated.
 3. The hydroxide ionscavenging system of claim 1, wherein halogen dioxide is generated ondemand.
 4. A hydroxide ion scavenging system for stabilizing a halogendioxide solution, said system comprising (a) from about 0.001% to about10% by weight of the total of a hydroxide ion scavenging-comprisinghalogen dioxide solution, a hydroxide ion scavenging system; and (b)from about 0.000001% to about 1% by weight of the total of a hydroxideion scavenging-comprising halogen dioxide solution, halogen dioxide;wherein said hydroxide ion scavenging agents are selected from the groupconsisting of: organic acids, salts of organic acids, inorganic acids,salts of inorganic acids, and mixtures thereof; further wherein saidhydroxide ion scavenging system is adapted to increase the concentrationof a halogen dioxide solution by at least about 5% in comparison to theconcentration of a corresponding halogen dioxide solution that does notcomprise said hydroxide ion-scavenging system, when both solutions aremeasured at 25° C., three hours following generation.
 5. The hydroxideion scavenging system of claim 4, wherein said hydroxide ion scavengingsystem is used to stabilize a chlorine dioxide solution.
 6. AnInterfacial Tension (IFT)-Lowering system for increasing the stabilityand/or efficacy of a halogen dioxide solution, said system comprising:(a) from about 0.00001% to about 10%, by weight of the total of anIFT-lowering system-comprising halogen dioxide precursor solution, anIFT-lowering system (b) from about 0.000001% to about 50%, by weight ofthe total of an IFT-lowering system-comprising halogen dioxide precursorsolution, one or more halogen salt precursors; wherein agents for use insaid IFT-lowering system are selected from the group consisting of:IFT-lowering polymers, IFT-lowering solvents, IFT-lowering surfactantsand mixtures thereof; further wherein said IFT-lowering system isadapted to convey at least about 5% greater reduction in the number ofmicrobes to the IFT-lowering system-comprising halogen dioxide solution,in comparison to a corresponding halogen dioxide solution that does notcomprise the said IFT-lowering system.
 7. An Interfacial Tension(IFT)-Lowering system for increasing the stability and/or efficacy of ahalogen dioxide solution, said system comprising: (c) from about0.00001% to about 10%, by weight of the total of an IFT-loweringsystem-comprising halogen dioxide solution, an IFT-lowering system (d)from about 0.000001% to about 1%, by weight of the total of anIFT-lowering system-comprising halogen dioxide solution, halogendioxide; wherein agents for use in said IFT-lowering system are selectedfrom the group consisting of: IFT-lowering polymers, IFT-loweringsolvents, IFT-lowering surfactants and mixtures thereof; further whereinsaid IFT-lowering system is adapted to convey at least about 5% greaterreduction in the number of microbes to the IFT-loweringsystem-comprising halogen dioxide solution, in comparison to acorresponding halogen dioxide solution that does not comprise the saidIFT-lowering system.
 8. The IFT-lowering system of claim 7, wherein saidIFT-lowering system is used to increase the efficacy of a chlorinedioxide solution.
 9. A halogen dioxide stabilizing andefficacy-increasing system, said system comprising the hydroxideion-scavenging system in accordance with claim 1 and the IFT-loweringsystem in accordance with claim 6; wherein said halogen dioxidestabilizing and efficacy-increasing system is characterized by aconcentration of halogen dioxide of at least about 5% greater theconcentration of a corresponding halogen dioxide that does not comprisesaid halogen dioxide stabilizing and efficacy-increasing system at 25°C., three hours following generation; further wherein said halogendioxide stabilizing and efficacy-increasing system is adapted to conveyat least about 5% greater reduction in the number of microbes than acorresponding halogen dioxide solution that does not comprise saidhalogen dioxide stabilizing and efficacy-increasing system.
 10. Ahalogen dioxide stabilizing and efficacy-increasing system, said systemcomprising the hydroxide ion-scavenging system in accordance with claim4 and the IFT-lowering system in accordance with claim 7; wherein saidhalogen dioxide stabilizing and efficacy-increasing system ischaracterized by a concentration of halogen dioxide of at least about 5%greater the concentration of a corresponding halogen dioxide that doesnot comprise said halogen dioxide stabilizing and efficacy-increasingsystem at 25° C., three hours following generation; further wherein saidhalogen dioxide stabilizing and efficacy-increasing system is adapted toconvey at least about 5% greater reduction in the number of microbesthan a corresponding halogen dioxide solution that does not comprisesaid halogen dioxide stabilizing and efficacy-increasing system.
 11. Ahalogen dioxide generating system, comprising: a) a source of an aqueousfeed solution comprising a halogen dioxide salt; b) a non-membraneelectrolysis cell comprising an anode and a cathode, and having a cellchamber with an inlet and an outlet; c) a means for passing the aqueousfeed solution into the chamber and along a passage adjacent to theanode, and out of the outlet; d) an electric current supply to flow acurrent through the aqueous feed solution in the passage, to convert aportion of the halogen dioxide salt to halogen dioxide, and thereby forman aqueous effluent comprising halogen dioxide; and e) a chambercomprising a system selected from the group consisting of: a hydroxideion scavenging system for stabilizing said halogen dioxide solution; anIFT-lowering system for increasing the stability and/or efficacy of saidhalogen dioxide solution and combinations thereof.
 12. The halogendioxide generating system of claim 11 wherein the anode and the cathodeare confronting and co-extensive, with a chamber gap of 1.0 mm or less.13. The halogen dioxide generating system of claim 11 wherein the anodeand the cathode are confronting and co-extensive, with a chamber gap of0.5 mm or less.
 14. The halogen dioxide generating system of claim 11wherein the anode and the cathode are confronting and co-extensive, witha chamber gap of 0.2 mm or less.
 15. The halogen dioxide generatingsystem of claim 11 wherein the anode is a conductive porous anode.
 16. Ahalogen dioxide generating system, comprising: a) a source of an aqueousfeed solution comprising a halogen dioxide salt; b) a non-membraneelectrolysis cell comprising an anode and a cathode, and having a cellchamber with an inlet and an outlet; c) a means for passing the aqueousfeed solution into the chamber and along a passage adjacent to theanode, and out of the outlet; d) an electric current supply to flow acurrent through the aqueous feed solution in the passage, to convert aportion of the halogen dioxide salt to halogen dioxide, and thereby forman aqueous effluent comprising halogen dioxide; and e) a chambercomprising both a hydroxide ion scavenging system and an IFT-loweringsystem for increasing the stability and efficacy of the halogen dioxidesolution.
 17. The halogen dioxide generating system of claim 16 whereinthe anode and the cathode are confronting and co-extensive, with achamber gap of 1.0 mm or less.
 18. The halogen dioxide generating systemof claim 16 wherein the anode and the cathode are confronting andco-extensive, with a chamber gap of 0.5 mm or less.
 19. The halogendioxide generating system of claim 16 wherein the anode and the cathodeare confronting and co-extensive, with a chamber gap of 0.2 mm or less.20. The halogen dioxide generating system of claim 16 wherein the anodeis a conductive porous anode.
 21. A halogen dioxide generating andre-circulating system, comprising: a) a source of an aqueous feedsolution comprising a halogen dioxide salt; b) a non-membraneelectrolysis cell comprising an anode and a cathode, and having a cellchamber with an inlet and an outlet; c) a means for passing the aqueousfeed solution into the chamber, and along a passage adjacent to theanode, and out of the outlet; d) an electric current supply to flow acurrent through the aqueous solution between the anode and the cathode,to convert at least a portion of the halogen dioxide salt in the passageto halogen dioxide, and thereby form an aqueous effluent comprisinghalogen dioxide; e) a means for delivering the aqueous effluent intocontact with a halogen dioxide depletion target, whereby a portion ofthe halogen dioxide in the aqueous effluent oxidizes the depletiontarget and reverts back to a halogen dioxide salt; f) a means forreturning the depleted effluent comprising the reverted halogen dioxidesalt back to the source; and g) a means for delivering a hydroxide ionscavenging system for stabilizing said halogen dioxide solution.
 22. Ahalogen dioxide generating and re-circulating system, comprising: a) asource of an aqueous feed solution comprising a halogen dioxide salt; b)a non-membrane electrolysis cell comprising an anode and a cathode, andhaving a cell chamber with an inlet and an outlet; c) a means forpassing the aqueous feed solution into the chamber, and along a passageadjacent to the anode, and out of the outlet; d) an electric currentsupply to flow a current through the aqueous solution between the anodeand the cathode, to convert at least a portion of the halogen dioxidesalt in the passage to halogen dioxide, and thereby form an aqueouseffluent comprising halogen dioxide; e) a means for delivering theaqueous effluent into contact with a halogen dioxide depletion target,whereby a portion of the halogen dioxide in the aqueous effluentoxidizes the depletion target and reverts back to a halogen dioxidesalt; f) a means for returning the depleted effluent comprising thereverted halogen dioxide salt back to the source; and g) a means fordelivering an IFT-lowering system for increasing the stability and/orefficacy of said halogen dioxide solution.
 23. A battery-poweredelectrolysis device for use to make on demand an aqueous solutioncomprising chlorine dioxide, comprising: a) an electrolysis cellcomprising an anode and a cathode, and having a cell chamber; b) a meansfor pumping an aqueous feed solution comprising a halogen dioxide saltinto the cell chamber and along a passage adjacent to the anode; c) abattery for flowing electrical current between the anode and the cathodewhen the aqueous feed solution flows within the chamber and along thepassage, whereby a portion of the halogen dioxide salt is converted tohalogen dioxide; and d) a means for delivering a hydroxide ionscavenging system for stabilizing said halogen dioxide solution.
 24. Thebattery-powered electrolysis device according to claim 23, wherein thedevice is a solution spray bottle, wherein the pumping means comprises aelectrically-driven pump that pumps solution from the bottle to theelectrolysis cell, and wherein the electrolysis cell comprises an anodeand a confronting, co-extensive cathode, having a cell chamber gap of1.0 mm or less.
 25. The battery-powered electrolysis device according toclaim 23, wherein the device is a solution spray bottle, wherein thepumping means comprises a electrically-driven pump that pumps solutionfrom the bottle to the electrolysis cell, and wherein the electrolysiscell comprises an anode and a confronting, co-extensive cathode, havinga cell chamber gap of 0.5 mm or less.
 26. The battery-poweredelectrolysis device according to claim 23, wherein the device is asolution spray bottle, wherein the pumping means comprises aelectrically-driven pump that pumps solution from the bottle to theelectrolysis cell, and wherein the electrolysis cell comprises an anodeand a confronting, co-extensive cathode, having a cell chamber gap of0.2 mm or less.
 27. A battery-powered electrolysis device for use tomake on demand an aqueous solution comprising chlorine dioxide,comprising: a) an electrolysis cell comprising an anode and a cathode,and having a cell chamber; b) a means for pumping an aqueous feedsolution comprising a halogen dioxide salt into the cell chamber andalong a passage adjacent to the anode; c) a battery for flowingelectrical current between the anode and the cathode when the aqueousfeed solution flows within the chamber and along the passage, whereby aportion of the halogen dioxide salt is converted to halogen dioxide; andd) a means for delivering an IFF-lowering system for increasing thestability and/or efficacy of said halogen dioxide solution.
 28. Thebattery-powered electrolysis device according to claim 27, wherein thedevice is a solution spray bottle, wherein the pumping means comprises aelectrically-driven pump that pumps solution from the bottle to theelectrolysis cell, and wherein the electrolysis cell comprises an anodeand a confronting, co-extensive cathode, having a cell chamber gap of1.0 mm or less.
 29. The battery-powered electrolysis device according toclaim 27, wherein the device is a solution spray bottle, wherein thepumping means comprises a electrically-driven pump that pumps solutionfrom the bottle to the electrolysis cell, and wherein the electrolysiscell comprises an anode and a confronting, co-extensive cathode, havinga cell chamber gap of 0.5 mm or less.
 30. The battery-poweredelectrolysis device according to claim 27, wherein the device is asolution spray bottle, wherein the pumping means comprises aelectrically-driven pump that pumps solution from the bottle to theelectrolysis cell, and wherein the electrolysis cell comprises an anodeand a confronting, co-extensive cathode, having a cell chamber gap of0.2 mm or less.
 31. A method of stabilizing halogen dioxide, said methodcomprising the step of delivering a hydroxide ion scavenging system to ahalogen dioxide solution for which increased stability is desired;wherein said method is adapted to increase the concentration of ahalogen dioxide solution by at least about 5% in comparison to theconcentration of a corresponding halogen dioxide solution that does notcontain said hydroxide ion scavenging system, when both solutions aremeasured at 25° C., three hours following generation; and wherein saidmethod is adapted to increase the efficacy of a chlorine dioxidesolution.
 32. A method of increasing the efficacy of halogen dioxide,said method comprising the step of delivering an Interfacial Tension(IFT)-lowering system to a halogen dioxide solution for which increasedefficacy is desired; wherein said method is adapted to increase theefficacy of a chlorine dioxide solution.
 33. A method of increasing thestability and efficacy of a halogen dioxide solution, said methodcomprising the step of delivering a hydroxide ion scavenging system andan Interfacial Tension (IFT)-lowering system to a halogen dioxidesolution for which increased stability and efficacy is desired.